zmodem upload ends up with strange error

Question

I'm currently trying to upload some files via zmodem to a small system with an embedded linux with busybox. While most files takes a long time through the 9600 BAUD connection, there is one file that always fails (cramfs_cmc-pu2_v2.45.img). With about 4MB it is also the largest one. For the upload I use Le Putty, a Putty fork that supports zmodem. Unfortunately there is no other method to upload files as the ftp server on that machine does not work properly.

The problem is that the upload always ends up with this strange stuff (after some hours of no feedback at all):

# /usr/bin/rz
Sending: cramfs_cmc-pu2_v2.45.img23be50
Bytes Sent:      0/4132864   BPS:0        ETA 00:00
®B@id@@íÁ@@htCJÁ®B@killíÁ@@htCJ®B@killall@íÁ@@htCJÁ®B@ln@@íÁ@@htCJ®B
@logger@@íÁ@@<H@Jº!@login@@@íÁ@@htCJÁ®B@ls@@íÁ@@htCJ®B@md5sum@@íÁ@@¿
@@JCø#@mgfestart@@@íÁ@@htCJ®B@mkdir@@@íÁ@@htCJ®B@mknod@@@íÁ@@htCJkH>
F¾#

I guessed that it runs out of flash memory but df gives me just

df: /proc/mounts: No such file or directory

Calculation of free space is difficult in that case anyway as the filesystem is jffs2.

Maybe there is anyone with an idea how to solve this problem with that ancient protocol. Thanks in advance.

Edit: Meanwhile I've splitted the file in many smaller ones and tried to upload them. It always fails after two files. This supports the suspicion that there is not enough free space.

Answer 1

Quite simple approach to check how much space there is left, even if you have no "df":

I just copied an existing file several times and the result was: "No space left on the device". So I'm pretty sure that the strange behaviour described above happened because of this.